1. Field
The subject matter disclosed herein relates to electronic devices, and more particularly to methods and apparatuses for use in and/or with a device capable of receiving satellite positioning system (SPS) signals from a plurality of navigation systems.
2. Information
Wireless communication systems are fast becoming one of the most prevalent technologies in the digital information arena. Satellite and cellular telephone services and other like wireless communication networks may already span the entire globe. Additionally, new wireless systems (e.g., networks) of various types and sizes are added each day to provide connectivity among a plethora of devices, both fixed and portable. Many of these wireless systems are coupled together through other communication systems and resources to promote even more communication and sharing of information.
Another popular and increasingly important wireless technology includes navigation systems and in particular those that are enabled for use with a satellite positioning system (SPS) that includes, for example, the global positioning system (GPS) and/or other like Global Navigation Satellite Systems (GNSSs). SPS enabled devices, for example, may receive wireless SPS signals that are transmitted by orbiting satellites of a GNSS and/or other terrestrial based transmitting devices. Received SPS signals may, for example, be processed to determine a corresponding GNSS system time, a range or pseudorange, an approximate or accurate geographical location, altitude, and/or velocity of the SPS enabled device. Consequently, various position and/or velocity estimation processes may be provided, at least in part, using an SPS enabled device.
Certain devices may be enabled to receive and process SPS signals transmitted by two or more GNSS or other like navigation systems. For example, certain devices may include one or more SPS receivers capable of receiving SPS signals from GPS and one or more other GNSS, such as, e.g., Galileo or GLONASS, or from Galileo and GLONASS, or other like combinations. Each GNSS has a specific corresponding ‘system time’ based on its particular clock. As there may be differences between such system times it may be difficult to use a mixture of different GNSS signals for position and/or velocity estimation processes at certain times. Accordingly, for this reason and/or others it may be useful to employ techniques that allow for a mixture of different GNSS signals to be used for position and/or velocity estimation processes in certain situations.